Most owl species are nocturnal and have become well adapted to night vision through their evolution, enabling them to hunt and catch their prey in the dark. Many prey species are nocturnal, thus availing diurnal predators during the say, so being nocturnal hunters can be a good strategy.

Nocturnal owls’ eyes have a number of adaptations for good night vision including their large size, the shape of their lenses, the large proportion of rods (light sensitive cells) to cones (colour-sensitive cells) in their retinas, and relatively large corneas.

However, some diurnal owls do not have particularly good vision in dark conditions, and instead are better adapted for hunting during the day.